<html>

<head></head>

<body>
    <h1>hello world</h1>
    {% set links=[
            ('Home', url_for('.index')), 
            ('About', url_for('.about')), 
            ]
    %}

    <nav>
        {% for label, href in links %}
            {% if loop.index is odd %} | {% endif %}
                <a href="{{ href }}">{{ label }}</a>
        {% endfor %}
    </nav>

</body>

</html>